1. Field of the Invention
The present invention relates to a zoom lens barrel used for optical equipment such as a camera and a projector, and optical equipment using the zoom lens barrel. In particular, the present invention relates to a zoom lens barrel, which has a moving diaphragm mechanism, and optical equipment using this.
2. Related Background Art
Heretofore, what is known as a moving diaphragm mechanism which is interlocked with the zooming of a zoom lens barrel and moves in the direction of an optical axis has such construction that a cam groove for a flare diaphragm is provided on the periphery of a cam ring, a driven pin which is a cam follower of a flare diaphragm member fits into the cam groove, and the flare diaphragm moves in the direction of an optical axis according to a cam action because the cam ring rotates with an optical axis as a center, like a lens barrel disclosed in Japanese Patent Application Laid-Open No. 2000-321476.
However, in the above-mentioned lens barrel, a cam groove for moving a diaphragm member is provided on a cam ring and the cam groove is provided in the same phase (area) as cam grooves for moving a zooming system lens group. Here, the phase means an angle (position) in a rotary direction with an optical axis of a zoom lens as a center, and the same phase means the same position (area) in a thrust direction of a zoom lens barrel. Thereby, since it is necessary to provide a cam groove for guiding the movement of a diaphragm member, separately from a plurality of cam grooves for a zoom lens in a thrust direction on a cam ring, the length of the cam ring in the thrust direction increases. In consequence, there arises a possibility that the size of a lens barrel increases.
In addition, when the cam grooves are worked by machining, the dedicated cam groove for the diaphragm member becomes necessary in addition to the cam grooves for the zooming system lens group. Hence, there arises a problem that processing cost increases.